74 lines
5.8 KiB
Markdown
74 lines
5.8 KiB
Markdown
---
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id: 587d825d367417b2b2512c96
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title: Depth-First Search
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challengeType: 1
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videoUrl: ''
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localeTitle: 深度优先搜索
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---
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## Description
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<section id="description">与<dfn>广度优先搜索</dfn>类似,这里我们将学习另一种称为<dfn>深度优先搜索的</dfn>图遍历算法。广度优先搜索搜索远离源节点的增量边长度,而<dfn>深度优先搜索</dfn>首先尽可能地沿着边缘路径向下<dfn>搜索</dfn> 。一旦到达路径的一端,搜索将回溯到具有未访问边缘路径的最后一个节点并继续搜索。在视觉上,这就是算法正在做的事情,其中顶部节点是搜索的起始点。 <img class="img-responsive" src="https://camo.githubusercontent.com/aaad9e39961daf34d967c616edeb50abf3bf1235/68747470733a2f2f75706c6f61642e77696b696d656469612e6f72672f77696b6970656469612f636f6d6d6f6e732f372f37662f44657074682d46697273742d5365617263682e676966">该算法的简单输出是可从给定节点到达的节点列表。因此,在实施此算法时,您需要跟踪您访问的节点。 </section>
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## Instructions
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<section id="instructions">编写一个函数<code>dfs()</code> ,它将无向,邻接矩阵<code>graph</code>和节点标签<code>root</code>作为参数。节点标签将只是<code>0</code>和<code>n - 1</code>之间节点的数值,其中<code>n</code>是图中节点的总数。您的函数应输出从<code>root</code>可到达的所有节点的数组。 </section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> ,起始节点为<code>1</code>应返回一个数组<code>0</code> , <code>1</code> , <code>2</code> ,和<code>3</code> 。'
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testString: 'assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 1);})(), [0, 1, 2, 3], "The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>1</code> should return an array with <code>0</code>, <code>1</code>, <code>2</code>, and <code>3</code>.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> ,起始节点为<code>1</code>应该返回一个包含四个元素的数组。'
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testString: 'assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 1);})().length === 4, "The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>1</code> should return an array with four elements.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> ,起始节点为<code>3</code>应该返回一个<code>3</code>的数组。'
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testString: 'assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]; return dfs(graph, 3);})(), [3], "The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> with a start node of <code>3</code> should return an array with <code>3</code>.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> ,起始节点为<code>3</code>应该返回一个包含一个元素的数组。'
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testString: 'assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]; return dfs(graph, 3);})().length === 1, "The input graph <code>[[0, 1, 0, 0], [1, 0, 1, 0], [0, 1, 0, 0], [0, 0, 0, 0]]</code> with a start node of <code>3</code> should return an array with one element.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> ,起始节点为<code>3</code>应该返回一个<code>2</code>和<code>3</code>的数组。'
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testString: 'assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 3);})(), [2, 3], "The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>3</code> should return an array with <code>2</code> and <code>3</code>.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> ,起始节点为<code>3</code>应该返回一个包含两个元素的数组。'
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testString: 'assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 3);})().length === 2, "The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>3</code> should return an array with two elements.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> ,起始节点为<code>0</code>应该返回一个<code>0</code>和<code>1</code>的数组。'
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testString: 'assert.sameMembers((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 0);})(), [0, 1], "The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>0</code> should return an array with <code>0</code> and <code>1</code>.");'
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- text: '输入图<code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> ,起始节点为<code>0</code>应该返回一个包含两个元素的数组。'
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testString: 'assert((function() { var graph = [[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]; return dfs(graph, 0);})().length === 2, "The input graph <code>[[0, 1, 0, 0], [1, 0, 0, 0], [0, 0, 0, 1], [0, 0, 1, 0]]</code> with a start node of <code>0</code> should return an array with two elements.");'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function dfs(graph, root) {
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}
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var exDFSGraph = [
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[0, 1, 0, 0],
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[1, 0, 1, 0],
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[0, 1, 0, 1],
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[0, 0, 1, 0]
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];
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console.log(dfs(exDFSGraph, 3));
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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